LIMESTONE HAWKSBEARD Crepis intermedia A. Gray Asteraceae – Aster family Corey L. Gucker and Nancy L. Shaw | 2020 ORGANIZATION NOMENCLATURE Limestone hawksbeard (Crepis intermedia A. Names, subtaxa, chromosome number(s), hybridization. Gray), belongs to the Asteraceae family and the Psilochaenia section of the Crepis genus (Bogler 2006; Enke 2009). Nomenclature in this review follows Bogler (2006). Range, habitat, plant associations, elevation, soils. NRCS Plant Code. CRIN4 (USDA NRCS 2019). Subtaxa. Crepis intermedia Nuttall var. intermedia (A. Gray) Jepson. Life form, morphology, distinguishing characteristics, reproduction. Synonym. Psilochenia intermedia (A. Gray) W.A. Common Names. Limestone hawksbeard, gray Growth rate, successional status, disturbance ecology, importance to hawksbeard, small-flower hawksbeard (USDA FS animals/people. 1937; Bogler 2006; Welsh et al. 2016; Hitchcock and Cronquist 2018). Current or potential uses in restoration. Chromosome Number. Chromosome numbers are: 2n = 33, 44, 55, 88 (Babcock and Stebbins 1938; Bogler 2006). Seed sourcing, wildland seed collection, seed cleaning, storage, Hybridization. Limestone hawksbeard is a testing and marketing standards. polyploid species that resulted from hybrid combinations involving two or three of the following hawksbeard species (Crepis spp.): Recommendations/guidelines for producing seed. tapertip hawksbeard (C. acuminata), largeflower hawksbeard (C. occidentalis), slender hawksbeard (C. exilis), Modoc hawksbeard (C. modocensis), or nakedstem hawksbeard (C. pleurocarpa) Recommendations/guidelines for producing planting stock. (Babcock and Stebbins 1938; Cronquist et al. 1994). Ongoing gene flow and intergradations are reported in areas where limestone hawksbeard occurs with any of the aforementioned Recommendations/guidelines, wildland restoration successes/ failures. hawskbeards or bearded hawksbeard (C. barbigera) (Breitung 1957; Whitton et al. 2008). Primary funding sources, chapter reviewers. DISTRIBUTION Bibliography. Limestone hawksbeard is a western species occurring in southern British Columbia, Alberta, Saskatchewan, and south to northern New Mexico, Arizona, and central California (Bogler 2006; Select tools, papers, and manuals cited. USDA NRCS 2019). It occurs primarily east of the Cascade Mountains in the Pacific Northwest Crepis intermedia A. Gray Crepis intermedia A. Gray. 1 (Hitchcock and Cronquist 2018). Populations are (A. tridentata subsp. tridentata) shrublands most abundant in northern California and southern occurring from 2,500 to 2,900 feet (760- Oregon, becoming local and infrequent eastward 880 m) in the Glass Mountain region of Mono (Babcock and Stebbins 1938). County, California (Horner 2001). In vegetation descriptions of south-central Nevada, including In a study that coupled herbarium records and the Nevada Test Site, limestone hawksbeard ecological niche modelling to describe the occupied an elevation range of 6,000-8,500 feet suitable climates for Great Basin forb species, (1,800-2,600 m). It occurred in singleleaf pinyon- increasing summer precipitation had a negative Utah juniper/big sagebrush (P. monophylla-J. effect on the potential climate suitability for osteosperma/A. tridentata) and curl-leaf mountain limestone hawksbeard in western sagebrush mahogany (Cercocarpus ledifolius)/big sagebrush (Artemisia spp.) ecosystems (Barga et al. 2018). communities and white fir (Abies concolor) forests Habitat and Plant Associations. Limestone (Beatley 1976). hawksbeard is one of the more widely distributed Elevation. The elevation range for limestone hawksbeard species (Babcock and Stebbins hawksbeard is 1,500 to 12,800 feet (460-3,900 m) 1938). Because it exhibits characteristics of its (Munz and Keck 1973; Bogler 2006). In Utah it is parent species, it is preadpated to changing 5,000 to 8,450 feet (1,525-2,575 m) (Welsh et al. conditions and capable of colonizing new habitats. 2016), and in California it is 1,500 to 10,500 feet In some parts of its range, this process is (460-3,200 m) (Munz and Keck 1973). considered aggressive. Although most common on arid, well-drained slopes at the lower edge of Soils. Populations are often associated with the ponderosa pine (Pinus ponderosa) forests in well-drained, stony soils (USDA FS 1937), but bunchgrass and sagebrush communities (Figs. 1 texture and parent material can vary. Limestone and 2), limestone hawksbeard has ascended hawksbeard occurred in serpentine soils in the higher into the glaciated valleys of the central Wentachee and Blue Mountains of Washington Sierra Nevada Mountains than any other and Oregon (Babcock and Stebbins 1938). In hawksbeard (Babcock and Stebbins 1938). California’s Lassen County, populations occupied heavy clay loams near Susanville and light clay loams near Horse Lake. Soils at both sites were nearly neutral with pH of 6.6 to 6.8. In the Sierra Nevada Mountains, limestone hawksbeard was frequent in basaltic and granitic soils (Babcock and Stebbins 1938). Although more common at lower elevations, limestone hawksbeard is found in the bristlecone pine (Pinus aristata) zone (9,500-10,000 ft [2,900- 3,000 m]) of the White Mountains in California. In this area, limestone hawksbeard was restricted to sandstone substrates and did not occur on dolomite or granite (Table 1). Sandstone soils Figure 1. Limestone hawksbeard growing in a big sagebrush/ had greater clay and available moisture and were grassland community in Utah. Photo: US Forest Service, closer to neutral pH than the dolomite and granite Rocky Mountain Research Station, Provo Shrub Sciences soils. Average annual precipitation in the study Laboratory (USFS RMRS PSSL). area from 1953 to 1962 was 12.5 inches (318 mm) (Wright and Mooney 1965). Limestone hawksbeard occupies rocky ridges, dry slopes, and open forests throughout its Table 1. Soil characteristics of three substrates in the range. Common plant associates include bristlecone pine zone of the White Mountains in California. Sandberg bluegrass (Poa secunda), wheatgrasses Limestone hawksbeard was restricted to sandstone soils (Elymus and Pseudoroegneria spp.), buckwheat (Wright and Mooney 1965). (Eriogonum spp.), lupine (Lupinus spp.), arrowleaf balsamroot (Balsamorhiza sagitatta), sagebrush, Soil characteristics Sandstone Dolomite Granite pinyon (Pinus spp.), juniper (Juniperus spp.), oak Sand (%) 63 64 82 (Quercus spp.), and mixed conifers (Standley 1921; Silt (%) 33 34 15 USDA FS 1937; Munz and Keck 1973; Bogler 2006; Lesica 2012; Welsh et al. 2016). Clay (%) 4 2 3 Avail moisture (%) 25 20 16 Limestone hawksbeard was described as pH 6 8 6 common and showy in dry basin big sagebrush 2 Crepis intermedia A. Gray In the Jackson Hole region of Wyoming, limestone hawksbeard was common in big sagebrush communities. Soils in these communities had about 1 inch (2.5 cm) of litter accumulation, an A horizon of fine sandy loam, which was about 3 inches deep (8 cm), followed by a thin B horizon of coarse sandy loam. Beneath the A and B horizons was a very coarse gravelly and stony mass of parent till 10 feet (3 m) or more deep (Reed 1952). Figure 3. Robust limestone hawksbeard plant growing in Utah. Photo: USFS RMRS PSSL. Figure 2. Limestone hawksbeard growing in a big sagebrush community in Utah. Photo: USFS RMRS PSSL. DESCRIPTION Limestone hawksbeard is a perennial from a slender to stout taproot and simple to branched caudex (Fig. 3) (Bogler 2006). The caudex, covered by dead basal leaves, gives rise to one or two erect, 10 to 28-inch (25-70 cm) tall stems (Babcock and Stebbins 1938; Bogler 2006; Welsh et al. 2016). Stems are branched, often covered in fine soft hairs, and exude a milky juice when damaged (Bogler 2006; Lesica 2012; Welsh et al. 2016). Plants produce basal and stem leaves. Stem leaves have long petioles that clasp the stems (Babcock and Stebbins 1938; Bogler 2006; Welsh et al. 2016). Lower leaves measure 4 to 16 inches (10-40 cm) long and 0.8 to 3.5 inches (2-9 cm) Figure 4. Limestone hawksbeard in flower. Note the wide (Munz and Keck 1973; Bogler 2006). They are indeterminate flowering and gray tomentose look of the elliptic, pointed at the apex, and pinnately lobed stems and leaves. Photo: USFS RMRS PSSL. half to three quarters of the way to the midvein. The triangular lobes are sometimes toothed Plants produce 10 to 60 flower heads in mostly (Babcock and Stebbins 1938; Bogler 2006; Lesica flat-topped, compound inflorescenses (Fig. 4) 2012; Welsh et al. 2016). Leaves, like the stems, (Babcock and Stebbins 1938; Bogler 2006). are sparsely to strongly gray tomentose (Fig. 4) Flower heads contain 7 to 16 florets (Babcock and (Babcock and Stebbins 1938). Stebbins 1938; Munz and Keck 1973). Involucres are narrowly cylindrical, 0.4 to 0.8 inch (1-2 cm) tall and less than a third as wide. The outer bracts are less than half as long as the inner bracts (Babcock and Stebbins 1938; Hitchcock and Crepis intermedia A. Gray Crepis intermedia A. Gray. 3 Cronquist 2018). Corollas are yellow and 0.5 to 1.2 inches (1.4-3 cm) long (Babcock and Stebbins ECOLOGY 1938; Munz and Keck 1973). Anther tubes when well developed are about 0.2-inch (0.5 cm) long In general, hawksbeard seedlings rapidly develop and typically abort without producing pollen. a long slender taproot but aboveground biomass Style branches are 2.5 to 3.5 mm long (Babcock production is slower. Plants are considered and Stebbins 1938). The fruit is a subcylindric long-lived and take 2 to 3 years to produce seed achene 0.2 to 0.4 inch (0.6-1 cm) long with tapered (Babcock and Stebbins 1938; James et al. 2009; ends. It is yellow to brown with 10 to 12 ribs and Ogle et al. 2012). The limited number of ecological a dusky white pappus 0.3 to 0.4 inch (0.7-1 cm) studies available suggest that limestone long (Babcock and Stebbins 1938; Bogler 2006; hawksbeard is found on recently disturbed sites Lesica 2012). Limestone hawksbeard represents and at some sites it is an aggressive invader a somewhat peculiar group of polyploid (Dalzell 2004; Babcock and Stebbins 1938). apomicts, which combine the features of multiple species including tapertip hawksbeard, Modoc Seed and Seedling Ecology.